Sheath insulator



March 26, 1935. E. D. EBY 1,995,884

I SHEATH INSULATOR Filed Oct. 22 1931 IhVentor: Eugene DEb y;

His Attorney.

Patented Mar. 26, 1935 UNITED STATES SHEATH INSULATOR Eugene D. Eby, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application October 22, 1931, Serial No. 570,415

2 Claims.

The present invention relates to insulators for insulating one section of a metal sheath of an electric cable from another, and particularly to insulators which can be applied to cables wherever desired without cutting or splicing the same.

My invention has for its object the provision of an improved form of insulator which is rugged, simple in construction and reliable in operation.

For a consideration of what I believe to be novel and. my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing which is illustrative of my invention,-Fig. l is a longitudinal section of a cable sheath insulator; Fig. 2 is a cross-section of the same, and Fig. 3 is a detail view of one of the joints.

The insulator shown is particularly intended to be applied to a cable which has already been installed and where it is undesirable to cut the conductor or the insulation thereon, but only to insulate one part of the sheath from another. Briefly stated, the insulator comprises a pair of metal supporting members which are jointed to the cable sheaths and a relatively massive ring of insulation located between the opposed faces of said members, said parts when mountedin place spanning a cutaway portion of the cable I sheath. Because the insulator has to be applied over an unbroken cable, the end members and ring are each made in two principal parts, the plane of division being axial.

3 indicates a stranded conductor over which is a body of insulation 4, for example, numerous layers of paper tape applied under suitable tension. Surrounding the insulation is a metallic sheath 5 made of lead or equivalent material. A short length of the sheath is removed as indicated at 6. Underrthe cut ends of the sheath is inserted a pair of thin metal bodies 7 and 8, both of annular or other suitable shape .and forming an electrostatic shield. The adjacent ends of the bodies are in overlapping relation and both are covered by hand applied tape wrapping 9 whereby one body is insulated from the other. The bodies may advantageously be "made of copper or equivalent braid. When the cable is of the shielded type, I may utilize one of the' shields toform one of the bodies.

Two metal end members or wiping sleeves 10 and 11 are provided to support the main insulator, each of which has a bore somewhat larger than the diameter of the sheath, and at its outer end is secured to its sheath by a wiped soldered joint 12. These metal end members are split to form halves, the plane of division being axial. The halves are provided with laterally extending registering lugs 13. In the lugs of one half are pins 14 which enter corresponding holes in the other lugs, and in this manner the halves are correctly aligned. Since the joint between the parts must be maintained fluid tight and since it is desirable to avoid gaskets wherever possible, the halves are soldered together. To do this, the outer edges of the joint are chamfered and the space thus formed is filled with solder 15 as .indicated in Fig. 3. After the soldering operation, the two parts of the member form an integral whole. They may be soldered before or after being wipe jointed to the sheath, but the former procedure is somewhat better. The metal membersare purposely made large enough to form a space or chamber for oil between their respective inner walls and the sheaths. Prior to making the wiped joints the members may be centered in position by means of wedges or equivalent devices.

Each end member has an enlarged flange 16 provided with a flat surface forming a seat for an annular gasket 17. This gasket preferably is somewhat elastic to take care of any inequalities in the meeting surfaces or of unequal pressures exerted by the clamping bolts. The gasket may be made of rubber compound which when subjected to pressure is highly resistant to oil or compound contained in the cable. The flange also has a series of holes to receive clamping bolts.

Between the metal end heads is a relatively massive ring insulator 19 made in halves, the plane of division being axial. The insulator is made of good tough molding material comprising fibrous material and a binder of which a phenolic condensation product is an example. It

has enlarged end flanges 20 and molded therein are parts of clamping means, in the present instance, two series of stud bolts 21, one series for each side. The outer ends of these bolts extend through the metal flanges 16 and the parts are clamped by suitable nuts. The opposed faces of the parts of the ring are made flat and between them are thin rectangular gaskets 22 which may be made of the same material as the end gaskets 17. In addition the parts of the ring are also provided with relatively massive lugs 23 arranged in pairs, and through each pair extends a through bolt 24, each having a suitable nut and lockwasher.

What I claim as new and desire to vsecure by Letters Patent of the United States, is:

1. A sheath insulator comprising a pair of metal end members having opposed seats, a relatively massive molded ring of insulating material located between and supported by the seats,

said ring being split in an axial plane and hav-,

ing side flanges, bolting means having a part 7 thereof molded in thefianges for clamping the 10 parts of the ring to the end members, andother bolts for uniting the parts of the ring. 

